"It is believed that it is the impact of this coverage which has prompted the jamming," the BBC said in a statement. "Satellite technicians have traced that interference and have confirmed it is coming from Iran."

The BBC said it suspected the Iranian authorities may have acted after an interactive TV show allowed Iranian and Egyptian viewers to exchange their views on the crisis.

Peter Horrocks, director of the BBC World Service, said it would continue to try to broadcast in the Islamic Republic.

"This jamming should stop immediately," he said. "It is wrong that our significant Iranian audience is being denied impartial news and information from BBC Persian TV.

"This is a regional story that Persian TV have been covering thoroughly and it is clear from our audience feedback that Iranian people want to know what is happening in Egypt."

The BBC's Persian Service is one of its oldest non-English language units. It was launched during World War Two in 1940 as a radio station and now delivers news via satellite television, mobile phones and the internet.

Iran has previously accused the BBC and other Western broadcasters of interfering in its affairs and trying to undermine the government.